The need for a receiver capable of monitoring two or more channels simultaneously has been recognized for a long time. However, there are several known fundamental problems with the implementation of a simultaneous dual channel receiver, especially when using a single Analog to Digital Converter (ADC) to digitize both channels simultaneously. Besides size and cost obstacles, there are several technical hurdles to overcome. These technical obstacles for implementing a Dual Watch (DW) simultaneous receiver system (SRS) include: front end signal splitting to enable both in-band and cross-band simultaneous dual channel reception; interference signals proximate to the first desired DW channel being mixed onto the second DW channel as co-channel interferers (near-far blocking); strong-to-weak signal operating conditions where the far-out transmitter noise from the first desired DW channel is mixed into the second DW channel thereby deleteriously affecting the second DW channel's Signal-to-Noise Ratio (SNR); and insuring that the ADC dynamic range is not limited. The occurrences of audio holes (absence of audio) are also to be avoided. Audio holes may occur when the receiver is in scan mode, whereby the receiver is monitoring for activity on alternate channels as may be included within a predetermined list of scan channels, and reverting back to an active/default channel.
While an alternative DW-SRS approach would be to add a second receiver in parallel to the first receiver system already in the radio product, such an alternative would incur significant cost and associated parts count penalties, power consumption and size penalties which would compromise product form factor and profitability.
Therefore, an efficient dual channel receiver architecture is needed that satisfies the above requirements with reasonable cost and size tradeoffs.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help improve understanding of various embodiments. In addition, the description and drawings do not necessarily require the order illustrated. It will be further appreciated that certain actions and/or steps may be described or depicted in a particular order of occurrence while those skilled in the art will understand that such specificity with respect to sequence is not actually required.
Apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the various embodiments so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. Thus, it will be appreciated that for simplicity and clarity of illustration, common and well-understood elements that are useful or necessary in a commercially feasible embodiment may not be depicted in order to facilitate a less obstructed view of these various embodiments.